- Oxidation of Flavone, 5-Hydroxyflavone, and 5,7-Dihydroxyflavone to Mono-, Di-, and Tri-Hydroxyflavones by Human Cytochrome P450 Enzymes
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Biologically active plant flavonoids, including 5,7-dihydroxyflavone (57diOHF, chrysin), 4′,5,7-trihydroxyflavone (4′57triOHF, apigenin), and 5,6,7-trihydroxyflavone (567triOHF, baicalein), have important pharmacological and toxicological significance, e.g., antiallergic, anti-inflammatory, antioxidative, antimicrobial, and antitumorgenic properties. In order to better understand the metabolism of these flavonoids in humans, we examined the oxidation of flavone, 5-hydroxyflavone (5OHF), and 57diOHF to various products by human cytochrome P450 (P450 or CYP) and liver microsomal enzymes. Individual human P450s and liver microsomes oxidized flavone to 6-hydroxyflavone, small amounts of 5OHF, and 11 other monohydroxylated products at different rates and also produced several dihydroxylated products (including 57diOHF and 7,8-dihydroxyflavone) from flavone. We also found that 5OHF was oxidized by several P450 enzymes and human liver microsomes to 57diOHF and further to 567triOHF, but the turnover rates in these reactions were low. Interestingly, both CYP1B1.1 and 1B1.3 converted 57diOHF to 567triOHF at turnover rates (on the basis of P450 contents) of >3.0 min-1, and CYP1A1 and 1A2 produced 567triOHF at rates of 0.51 and 0.72 min-1, respectively. CYP2A13 and 2A6 catalyzed the oxidation of 57diOHF to 4′57triOHF at rates of 0.7 and 0.1 min-1, respectively. Our present results show that different P450s have individual roles in oxidizing these phytochemical flavonoids and that these reactions may cause changes in their biological and toxicological properties in mammals.
- Nagayoshi, Haruna,Murayama, Norie,Kakimoto, Kensaku,Tsujino, Masaki,Takenaka, Shigeo,Katahira, Jun,Lim, Young-Ran,Kim, Donghak,Yamazaki, Hiroshi,Komori, Masayuki,Guengerich, F. Peter,Shimada, Tsutomu
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Read Online
- Continuous flow microchannel synthesis process of flavonoid compounds
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The invention provides a continuous flow microchannel synthesis process of flavonoid compounds. According to the process, hesperidin and iodine elementary substance are used as raw materials and react in a continuous flow microchannel reactor in the presence of a reaction solvent to synthesize the flavonoid compound as shown in a formula A. Compared with a traditional kettle-type preparation process, the process disclosed by the invention has the advantages that the preparation time is obviously shortened, and the conversion rate of raw materials and the yield of products are obviously improved; and especially, when the diosmin is prepared under optimal process conditions of continuous flow microchannel synthesis, the conversion rate of the raw material hesperidin is as high as 96.48%, and the yield of the product diosmin is as high as 81.96%. The continuous flow micro-channel synthesis process provided by the invention is beneficial to realizing safe, efficient and rapid industrial production of flavonoid compounds, and has a wide application prospect.
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Paragraph 0050-0060
(2021/06/22)
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- Novel chromenone derivatives having substituted biphenyl group and a pharmaceutical composition for prevention or treatment of allergic diseases compring the same
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The present invention relates to: a novel chromenone derivative compound capable of effectively suppressing an allergic immune response by inhibiting signal transduction mediated by thymic stromal lymphopoietin (TSLP); and a pharmaceutical composition capable of fundamentally preventing or treating various allergic diseases by using the same.COPYRIGHT KIPO 2021
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- Scope and Mechanism of the Ruthenium-Catalyzed Dehydrative C-H Coupling of Phenols with α,β-Unsaturated Carbonyl Compounds: Expedient Synthesis of Chromene and Benzoxacyclic Derivatives
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Chromene and benzoxacyclic derivatives were efficiently synthesized from the ruthenium-catalyzed dehydrative C-H coupling reaction of phenols with α,β-unsaturated carbonyl compounds. The cationic ruthenium-hydride complex was found to be an effective catalyst for the coupling and annulation of phenols with enals to form chromene products. The coupling of phenols with linear enones afforded 2,4-disubstituted chromene derivatives, whereas the analogous coupling with cyclic enones yielded 9-hydroxybenzoxazole products. The reaction of 3,5-dimethoxyphenol with PhCH=CHCDO resulted in the chromene product with a significant H/D exchange to both benzylic and vinyl positions. The most significant carbon isotope effect from the coupling of 3,5-dimethoxyphenol with 4-methoxycinnamaldehyde was observed on the α-olefinic carbon of the chromene product (C(2) = 1.067). A Hammett plot from the coupling of 3,5-dimethoxyphenol with para-substituted p-X-C6H4CH=CHCHO displayed a linear correlation, with a strong promotional effect by an electron-withdrawing group (ρ = +1.5; X = OCH3, CH3, H, F, Cl). Several biologically active chromenone derivatives were synthesized by using the catalytic coupling method. The catalytic method provides an expedient synthetic protocol for the coupling of phenols with α,β-unsaturated carbonyl compounds without employing reactive reagents or forming any wasteful byproducts.
- Mokar, Bhanudas Dattatray,Yi, Chae S.
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p. 4625 - 4632
(2019/12/24)
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- Design, synthesis and biological evaluation of 2-Phenyl-4H-chromen-4-one derivatives as polyfunctional compounds against Alzheimer’s disease
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Polyfunctional compounds comprise a novel class of therapeutic agents for the treatment of multi-factorial diseases. A series of 2-Phenyl-4H-chromen-4-one and its derivatives (5a–n) were designed, synthesized, and evaluated for their poly-functionality against acetylcholinestrase (AChE) and advanced glycation end products (AGEs) formation inhibitors against Alzheimer’s disease (AD). The screening results showed that most of them exhibited a significant ability to inhibit AChE AGEs formation with additional radical scavenging activity. Especially, 5m, 5b, and 5j displayed the greatest ability to inhibit AChE (IC50 = 8.0, 8.2, and 11.8 nM, respectively) and AGEs formation (IC50 = 55, 79, and 54 μM, respectively) with good antioxidant activity. Molecular docking studies explored the detailed interaction pattern with active, peripheral, and mid-gorge sites of AChE. These compounds, exhibiting such multiple pharmacological activities, can be further taken a lead for the development of potent drugs for the treatment of Alzheimer’s disease.
- Singh, Manjinder,Kaur, Maninder,Vyas, Bhawna,Silakari, Om
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p. 520 - 530
(2017/10/09)
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- Unveiling the 6,8-Rearrangement in 8-Phenyl-5,7-dihydroxyflavylium and 8-Methyl-5,7-dihydroxyflavylium through Host–Guest Complexation
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8-Phenyl-5,7-dihydroxyflavylium and 8-methyl-5,7-dihydroxyflavylium were synthesized to observe the 6,8-rearrangement. 8-Phenyl and 8-methyl residues were introduced by Suzuki–Miyaura reaction of 8-iodochrysin, then reduced by LiAlH4 to give the corresponding 3-deoxyanthocyanidins. At pH 1.0 the stable form is the 8-substituted flavylium cation in both compounds. At higher pH values the quinoidal bases are the stable species and some evidence for the 6,8-rearrangement was obtained, but the respective spectral variations are very small. This was overcome by using a modified cyclodextrin (captisol), which favors the formation of the trans-chalcone at the expense of the quinoidal bases. The trans-chalcone was isolated and dissolved in CD3OD/DCl (pD + m/z 253). The 6-isomer slowly reverts to the most stable 8-isomer. The 6,8-rearrangement was also observed after irradiation of the trans-chalcone (in the presence of captisol) at pH 5. Acidification of this photostationary state gave a mixture of both flavylium cations. The UV/Vis absorption of the flavylium cation (6-isomer) was blueshifted in comparison to the 8-isomer.
- Basílio, Nuno,Lima, Jo?o Carlos,Cruz, Luís,de Freitas, Victor,Pina, Fernando,Ando, Hiroki,Kimura, Yuki,Oyama, Kin-Ichi,Yoshida, Kumi
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p. 5617 - 5626
(2017/10/13)
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- A transition-metal-free fast track to flavones and 3-arylcoumarins
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A highly regioselective and transition-metal free one-pot arylation of chromenones with arylboronic acids has been achieved employing K2S2O8. The procedure consists of a sequence of some reactions including an arylation/decarboxylation cascade and proceeds well in aqueous media to afford biologically interesting flavones and 3-arylcoumarins. This method exhibited excellent selectivity and functional group tolerance under mild conditions. The reaction also showed perfect efficacy for the preparation of styryl coumarins.
- Golshani, Mostafa,Khoobi, Mehdi,Jalalimanesh, Nafiseh,Jafarpour, Farnaz,Ariafard, Alireza
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supporting information
p. 10676 - 10679
(2017/10/06)
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- Facile synthesis of acacetin and its derivatives
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Acacetin, a O-methylated bioflavonoid isolated from the traditional Chinese medicine Xuelianhua (Saussurea tridactyla), is a promising orally effective atrium-selective antiarrhythmic agent for the treatment of atrial fibrillation (AF). Here we describe an efficient two-component method for the synthesis of acacetin and its derivatives.
- Zhao, Yuan,Cai, Li,Sui, Qiang,Lin, Feng,Jiang, Wen,Chen, Jianli,Lu, Weigeng,Gao, Qi
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supporting information
p. 3577 - 3580
(2016/07/21)
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- Novel synthesised flavone derivatives provide significant insight into the structural features required for enhanced anti-proliferative activity
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With many cancers showing resistance to current chemotherapies, the search for novel anti-cancer agents is attracting considerable attention. Natural flavonoids have been identified as useful leads in such programmes. However, since an in-depth understanding of the structural requirements for optimum activity is generally lacking, further research is required before the full potential of flavonoids as anti-proliferative agents can be realised. Herein a broad library of 76 methoxy and hydroxy flavones, and their 4-thio analogues, was constructed and their structure-activity relationships for anti-proliferative activity against the breast cancer cell lines MCF-7 (ER +ve), MCF-7/DX (ER +ve, anthracycline resistant) and MDA-MB-231 (ER -ve) were probed. Within this library, 42 compounds were novel, and all compounds were afforded in good yields and >95% purity. The most promising lead compounds, specifically the novel hydroxy 4-thioflavones 15f and 16f, were further evaluated for their anti-proliferative activities against a broader range of cancer cell lines by the National Cancer Institute (NCI), USA and displayed significant growth inhibition profiles (e.g. compound-15f: MCF-7 (GI50 = 0.18 μM), T-47D (GI50 = 0.03 μM) and MDA-MB-468 (GI50 = 0.47 μM) and compound-16f: MCF-7 (GI50 = 1.46 μM), T-47D (GI50 = 1.27 μM) and MDA-MB-231 (GI50 = 1.81 μM)). Overall, 15f and 16f exhibited 7-46 fold greater anti-proliferative potency than the natural flavone chrysin (2d). A systematic structure-activity relationship study against the breast cancer cell lines highlighted that free hydroxyl groups and the B-ring phenyl groups were essential for enhanced anti-proliferative activities. Substitution of the 4-CO functionality with a 4-CS functionality, and incorporation of electron withdrawing groups at C-4′ of the B-ring phenyl, also enhanced activity. Molecular docking and mechanistic studies suggest that the anti-proliferative effects of flavones 15f and 16f are mediated via ER-independent cleavage of PARP and downregulation of GSK-3β for MCF-7 and MCF-7/DX cell lines. For the MDA-MB-231 cell line, restoration of the wild-type p53 DNA binding activity of mutant p53 tumour suppressor gene was indicated.
- Ravishankar, Divyashree,Watson, Kimberly A.,Greco, Francesca,Osborn, Helen M. I.
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p. 64544 - 64556
(2016/07/21)
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- Aldose reductase inhibitors for diabetic complications: Receptor induced atom-based 3D-QSAR analysis, synthesis and biological evaluation
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Herein, atom-based 3D-QSAR analysis was performed using receptor-guided alignment of 46 flavonoid inhibitors of aldose reductase (ALR2) enzyme. 3D-QSAR models were generated in PHASE programme, and the best model corresponding to PLS factor four (QSAR4), was selected based on different statistical parameters (i.e., Rtrain2, 0.96; Qtest2 0.81; SD, 0.26). The contour plots of different structural properties generated from the selected model were utilized for the designing of five new congener molecules. These designed molecules were duly synthesized, and evaluated for their in vitro ALR2 inhibitory activity that resulted in the micromolar (IC50 22 μM) activity of all molecules. Thus, the newly designed molecules having ALR inhibitory potential could be employed for the management of diabetic complications.
- Vyas, Bhawna,Singh, Manjinder,Kaur, Maninder,Bahia, Malkeet Singh,Jaggi, Amteshwar Singh,Silakari, Om,Singh, Baldev
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supporting information
p. 59 - 71
(2015/05/05)
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- Synthesis, characterization and molecular docking studies of novel 2-amino 3-cyano pyrano[2,3H]chrysin derivatives as potential antimicrobial agents
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A series of novel 2-amino 3-cyano 4-aryl pyrano[2,3H]chrysin derivatives (3a-m) were efficiently synthesized by one-pot three-component reaction of aromatic aldehydes, malononitrile and chrysin and characterized by 1H NMR, 13C NMR and mass spectral data. All the newly synthesized compounds were evaluated for their in vitro antimicrobial activity (antibacterial and antifungal). Among the tested compounds, 3a, 3g, 3h, 3j and 3k showed potent antibacterial activity compared to ciprofloxacin and the compounds 3a, 3g, 3h, 3i and 3k showed excellent antifungal activity compared to itrazole. The compounds 3a, 3g, 3h and 3k exhibited potent antimicrobial activity against all the selected pathogenic bacteria and fungi and emerged as potential molecules for further development. In addition, molecular modeling studies also performed to delineate the putative binding mode of these compounds. All of these chrysin derivatives (3a-m) obeyed the Lipinski's "rule of five" and have drug-likeness. Docking scores with appreciable binding energy values also exactly correlated with the experimental antimicrobial activity. The chemscore estimated by GOLD software was found to have a good correlation with the experimental inhibitory activity. Graphical Abstract: Docking of compound 3g with protein[Figure not available: see fulltext.] A series of novel 2-amino 3-cyano pyrano[2,3H]chrysin derivatives (3a-m) has been synthesized and evaluated for their antimicrobial activity along with molecular modeling studies[Figure not available: see fulltext.]
- Ramesh,Reddy, Ch. Sanjeeva,Suresh Babu,Reddy, P. Muralidhar,Srinivasa Rao,Parthasarathy
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p. 3696 - 3709
(2015/09/07)
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- Ru(II)-Catalyzed Site-Selective Hydroxylation of Flavone and Chromone Derivatives: The Importance of the 5-Hydroxyl Motif for the Inhibition of Aurora Kinases
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An efficient protocol for Ru(II)-catalyzed direct C-H oxygenation of a broad range of flavone and chromone substrates was developed. This convenient and powerful synthetic tool allows for the rapid installation of the hydroxyl group into the flavone, chromone, and other related scaffolds and opens the way for analog synthesis of highly potent Aurora kinase inhibitors. The molecular docking simulations indicate that the formation of bidentate H-bonding patterns in the hinge regions between the 5-hydroxyflavonoids and Ala213 was the significant binding force, which is consistent with experimental and computational findings.
- Kim, Kiho,Choe, Hyeonjeong,Jeong, Yujeong,Lee, Jun Hee,Hong, Sungwoo
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supporting information
p. 2550 - 2553
(2015/05/27)
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- Development of a concise synthesis of the flavonoid chrysin
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Two novel routes for the synthesis of the flavonoid chrysin are described. In the first, 3,5-dimethoxyphenol (taxicatigenin) was converted to 2-hydroxy-4,6-dimethoxyacetophenone and then by condensation with benzaldehyde to 2'-hydroxy-4',6'-dimethoxychalcone. The latter was cyclised with iodine and demethylated with pyridine hydrochloride to form chrysin in 50% overall yield. In the second route, taxicatigenin was acylated with cinnamoyl chloride to form a chalcone under special conditions. This was then converted to chrysin in 42% and 56% overall yield, respectively. Several disadvantages of previous syntheses like long reaction time, tedious work-up and low overall yield have been overcome.
- Wang, Qian,Cui, Wei,Yang, Jian,Yang, Bo
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p. 300 - 302
(2015/06/02)
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- Synthesis and anti-inflammatory in vitro, in silico, and in vivo studies of flavone analogues
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Chrysin and 7-hydroxy flavone were prepared by Baker-Venkatraman rearrangement followed by esterification at 7th position and replacement of ester with acetamide linking to different heterocyclic moieties synthesized 13a-g and 14a-g series of flavones analogues. These were screened against COX-2 and COX-1 enzymes for inhibition by in vitro assay and COX-2 for in silico docking studies. The compound 14a was found to be most active with IC50 of 3.11 μM concentration, with highest binding energy of -12.4 kcal/mole and 77.2 and 80.5 % inhibition at 3 and 5 h post-carrageenan induced in paw oedema.
- Khanapur, Manjulatha,Pinna, Nishal K.,Badiger, Jaishree
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p. 2656 - 2669
(2015/02/05)
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- A new synthesis for acacetin, chrysoeriol, diosmetin, tricin and other hydroxylated flavones by modified Baker-Venkataraman transformation
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Baker-Venkataraman (BV) rearrangement is the method of choice for the synthesis of flavones. The major limitation of BV is that it requires extensive protections and deprotections of hydroxyl groups which make the process lengthy and cumbersome. In the present study, a three step efficient method has been developed using simple protecting groups and easily available starting materials. New syntheses for acacetin, chrysoeriol, diosmetin, tricin and other hydroxylated flavones are described.
- Pandurangan
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p. 225 - 229
(2014/05/20)
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- An efficient synthesis of chrysin
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Two routes for the synthesis of the flavones chrysin are described. In the first 1,3,5-trimethoxybenzene was converted to 2-hydroxy-4,6- dimethoxyacetophenone and then by condensation with benzaldehyde to 2′-hydroxy-4′,6′-dimethoxychalcone. The latter was cyclised with iodine and demethylated with pyridine hydrochloride to form chrysin in 53% overall yield. In the second route, 1,3,5-trimethoxybenzene was acylated with cinnamic acid to form the chalcone which was then converted to chrysin in 30.7% overall yield.
- Liu, Man,Zhang, Ji,Yang, Jian,Yang, Bo,Cui, Wei
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p. 134 - 136
(2014/04/17)
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- Multifunctional tacrine-flavonoid hybrids with cholinergic, β-amyloid-reducing, and metal chelating properties for the treatment of Alzheimer's disease
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A new series of tacrine-flavonoid hybrids (13a-u) had been designed, synthesized, and evaluated as multifunctional cholinesterase (ChE) inhibitors against Alzheimer's disease (AD). In vitro studies showed that most of the molecules exhibited a significant ability to inhibit ChE and self-induced amyloid-β (Aβ1-42) aggregation. Kinetic and molecular modeling studies also indicated compounds were mixed-type inhibitors, binding simultaneously to active, peripheral and mid-gorge sites of AChE. Particularly, compound 13k was found to be highly potent and showed a balanced inhibitory profile against ChE and self-induced Aβ1-42 aggregation. Moreover, it also showed excellent metal chelating property and low cell toxicity. These results suggested that 13k might be an excellent multifunctional agent for AD treatment.
- Li, Su-Yi,Wang, Xiao-Bing,Xie, Sai-Sai,Jiang, Neng,Wang, Kelvin D.G.,Yao, He-Quan,Sun, Hong-Bin,Kong, Ling-Yi
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p. 632 - 646
(2013/10/22)
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- Synthesis and antidiabetic activity of 5,7-dihydroxyflavonoids and analogs
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In a study to evaluate the structural elements essential for the antidiabetic activity of flavonoids, we synthesized two series of flavonoids, 5,7-dihydroxyflavanones and 5,7-dihydroxyflavones. In a screening for potential antidiabetic activity, most of the flavonoids showed a remarkable in vitro activity, and compounds 1f, 2d, and 3c were significantly more effective than the positive control, metformin. The biological activity was mainly affected by structural modification at the ring B moiety of the flavonoid skeleton. The results suggest that 5,7-dihydroxyflavonoids can be considered as promising candidates in the development of new antidiabetic lead compounds. Copyright
- Chang, Liu-Shuan,Li, Chun-Bao,Qin, Nan,Jin, Mei-Na,Duan, Hong-Quan
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scheme or table
p. 162 - 169
(2012/04/04)
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- Lewis acid-triggered selective zincation of chromones, quinolones, and thiochromones: Application to the preparation of natural flavones and isoflavones
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A Lewis acid-triggered zincation allows the regioselective metalation of various chromones and quinolones. In the absence of MgCl2, a C(3) zincation is observed, whereas in the presence of MgCl2 or a related Lewis acid, C(2) zincation occurs. Applications to a natural flavone, isoflavone, and quinolone are shown.
- Klier, Lydia,Bresser, Tomke,Nigst, Tobias A.,Karaghiosoff, Konstantin,Knochel, Paul
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p. 13584 - 13587
(2012/10/08)
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- Synthesis and cytotoxicity of novel chrysin derivatives
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A series of chrysin derivatives 8a-8v were prepared and tested in vitro against HCT-116 (human colon cancer cell line), Hela (human cervical carcinoma cell line), DU-145 (human prostate cell line), K562 (human leukemia cell line), and SGC-7901 (human gastric cancer cell line). The chemical structures of these compounds were confirmed by means of MS, IR, 1H NMR, 13C NMR, and elemental analysis. Among these derivatives, 7-(2-(piperazin-1- yl)ethoxy)-5-hydroxy-2-phenyl-4H-chromen-4-one, 8n, had the strongest activity against HCT-116, Hela, DU-145, K562, and SGC-7901 cells. Springer Science+Business Media, LLC 2010.
- Hu, Kun,Wang, Wei,Cheng, Hong,Pan, ShaSha,Ren, Jie
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p. 838 - 846
(2012/05/04)
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- A new flavone glycoside from the aerial part of Scutellaria schachristanica
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The new flavone glycoside schachristanoside was isolated from the aerial part of Scutellaria schachristanica Zuz. (Lamiaceae). Spectral data and chemical transformations found that schachristanoside had the structure chrysin-7-O-[α-L-arabinopyranosyl-(1∈→∈6)] -β-D-glucopyranoside.
- Tashmatov,Eshbakova,Bobakulov, Kh. M.
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experimental part
p. 547 - 549
(2011/12/14)
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- Chemical constituents from cassia occidentalis Linn
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The present paper deals with the isolation and structural elucidation of three new compounds 1, 2 and 3 from the seeds of Cassia occidentalis Linn. These compounds have been characterized as 5, 7-dihydroxyflavone-5-O-β-D- xylopyranosyl-7-O-α-L-rhamnopyranosyl-(1→3)-O-α-L- arabinopyranoside (1), 3, 5, 7, 3′,4′-pentahydroxy flavone-3-O-α-L-rhamnopyranosyl-7-O-β-D-glucopyranosyl-(1→3) -O-β-D-xylopyranoside (2) and 5, 7, 3′, 4′-tetrahydroxy-6- methoxyflavone-5-O-α-L-ara-binopyranosyl-(1→4)-O-α-L- rhamnopyranosyl-(1→3)-O-β-D-galactopyranoside (3) respectively by various colour reactions, chemical degradations and spectral analysis. These compounds have been evaluated against various bacteria and fungi which showed good results.
- Yadava,Satnami
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body text
p. 1112 - 1118
(2011/10/09)
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- An efficient one-pot synthesis of flavones
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Flavones were prepared using a one-pot procedure starting from the corresponding 2′-hydroxyacetophenones. The latter were treated with 3 equiv of aroyl chloride in wet K2CO3/acetone (1% w/w water) to afford a good yield of flavone and a smaller amount of 3-aroylflavone. Evidence was obtained that the reaction proceeds via a triketone intermediate. When the reactants were heated in 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and pyridine, the 3-aroylflavone was obtained exclusively. Use of a stoichiometric amount of aroyl chloride afforded only the corresponding flavone.
- Chee, Chin Fei,Buckle, Michael J.C.,Rahman, Noorsaadah Abd.
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supporting information; experimental part
p. 3120 - 3123
(2011/06/26)
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- Reactions of carbanions with 1,3-benzodioxin-4-ones: Facile routes to flavones, aurones, and acyl phloroglucinols
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Two 1,3-benzodioxin-4-ones react with enolates, acetylides and aryllithium reagents to afford adducts that were converted into flavones, aurones, and an acyl phloroglucinol. Georg Thieme Verlag Stuttgart.
- Kraus, George A.,Wie, Jingqiang,Thite, Aniket
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experimental part
p. 2427 - 2431
(2009/04/06)
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- COMPOUNDS FOR IMMUNOPOTENTIATION
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Methods of stimulating an immune response and treating patients responsive thereto with 3,4-di(1H-indol-3-yl)-1H-pyrrole-2,5-diones, staurosporine analogs, derivatized pyridazines, chromen-4-ones, indolinones, quinazolines, nucleoside analogs, and other small molecules are disclosed.
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Page/Page column 118
(2010/02/15)
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- Synthesis and properties of 3-acyl-γ-pyrones, a novel class of flavones and chromones
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Using modified Baker-Venkataraman reaction a novel class of 3-acyl flavones and chromones have been synthesised. Reaction mechanism for their formation have been elucidated. The properties of 3-acyl flavonoids indicate them to be precursors for the synthesis of flavones.
- Ganguly,Kaur,Mahata,Biswas,Pramanik,Chan
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p. 4119 - 4121
(2007/10/03)
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- Solvent-free synthesis of functionalized flavones under microwave irradiation
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(Chemical Equation Presented) Eco-friendly direct solvent-free synthesis of flavones is achieved by microwave irradiation of phloroglucinol and β-ketoesters. Heating with microwaves versus under classical conditions was shown to be higher yielding, cleaner, and faster. The reaction goes through a cycloaddition of an α-oxo ketene intermediate followed by an uncatalyzed thermal Fries rearrangement.
- Seijas, Julio A.,Vazquez-Tato, M. Pilar,Carballido-Reboredo, Raquel
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p. 2855 - 2858
(2007/10/03)
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- Silica gel supported InBr3 and InCl3: New catalysts for the facile and rapid oxidation of 2′-hydroxychalcones and flavanones to their corresponding flavones under solvent free conditions
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Silica gel supported InBr3 or InCl3 (15-20 mol %) were explored as a new solid-support catalysts for the facile and efficient oxidation, under solvent free conditions, of 2′-hydroxychalcones and flavanones to yield the corresponding flavones in >80% yield. The catalysts are easily prepared, stable, and efficient under mild reaction conditions.
- Ahmed, Naseem,Ali, Hasrat,Van Lier, Johan E.
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p. 253 - 256
(2007/10/03)
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- Cleavage of methyl ethers of flavones by chloroaluminate ionic liquid
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A new o-demethylation method of a series of mono-, di-, trimethoxy-flavones using a chloroaluminate ionic liquid - [BMIM] [Al2Cl7] in dichloromethane is described. The desired products were obtained in moderate to good yields.
- Liu, Tao,Hu, Yongzhou
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p. 3209 - 3218
(2007/10/03)
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- Method for the reduction of the mammalian appetite
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The present invention relates to a method for the treatment and/or prevention of overweight and to a method for the reduction of a mammalian appetite. The present method comprises the administration to the mammal of a dosage containing an effective amount of a flavonoid selected from the group consisting of chrysin, flavone, precursors of these flavonoids that are convertible into the one of these flavonoids by gastrointestinal hydrolytic cleavage and mixtures thereof.
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- An efficient synthesis of neoflavonoid antioxidants based on Montmorillonite K-10 catalysis
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A new approach to synthesis of neoflavonoids, based on a high yielding Montmorillonite K-10 catalyzed lactone ring forming cyclization process, is described. The utility of this methodology is exemplified by its employment in the preparation of the substituted 4-phenylneoflavonoids 1-8. The free radical scavenging properties of these substances were evaluated. The neoflavonoids 1 and 5, which mimic esculetin-type antioxidants, were observed to quench hydrazyl free radicals.
- Lee,Tseng,Lee
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p. 2247 - 2254
(2007/10/03)
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- A rational approach to the design of flavones as xanthine oxidase inhibitors
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In the light of previous QSAR studies on flavones as inhibitors of xanthine oxidase, we synthesized and tested a new series of 7-hydroxyflavones carrying a wide and balanced variety of substituents (π, σ(p)) at the 4' position in order to explore the effect of substituents at this position on the xanthine oxidase inhibitory activity. The results of pK(a) determinations show that the electronic effects of the substituents are not transferred to the hydroxyl at C7, previously found to be fundamental for activity. An excellent correlation is found between molar refractivity of the substituents and the inhibitory activity. These results, applied to the more active 5,7-dihydroxyflavones, allowed the design and synthesis of a very active inhibitor, with an IC50 in the nanomolar range. On interpretative grounds, C4' substituents of flavones are involved in dispersion interactions with the enzyme. The calculation of quantum chemical polarizabilities and solvent accessible surface areas suggests the existence of π-π stacking interactions with an aromatic aminoacidic residue of the enzyme.
- Costantino,Rastelli,Albasini
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p. 693 - 699
(2007/10/03)
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- Cyclodehydrogenation of 2'-Hydroxychalcones with Hypervalent Iodine Reagent: A New Synthesis of Flavones
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A new synthesis of chrysin (1) and luteolin (4) was accomplished by the cyclodehydrogenation of the appropriately substituted 2'-hydroxychalcones 21 and 22 in the presence of iodosobenzene diacetate/potassium hydroxide in methanol.The scope and limitation of this transformation is discussed. - Keywords: Cyclodehydrogenation / 2'-Hydroxychalcones / Flavones / Iodosobenzene diacetate
- Litkei, Gyoergy,Gulasci, Katalin,Antus, Sandor,Blasko, Gabor
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p. 1711 - 1716
(2007/10/02)
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- Flavonoids, 45 . A General and Efficient Synthesis of Hydroxyflavones and -chromones
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An efficient and versatile method for the synthesis of flavones hydroxylated in either ring A or B and of chromones hydroxylated in is described.This approach is based on the acidic resin-promoted cyclodehydration and simultaneous deprotection of methoxymethoxylated 1-(2-hydroxyphenyl)propane-1,3-diones easily available by either the Baker-Venkataraman rearrangement or the Claisen condensation. - Key words: Amberlyst 15 / Baker-Venkataraman rearrangement / Claisen condensation / hydroxychromone / hydroxyflavone / methoxymethyl protection
- Patonay, Tamas,Molnar, Denes,Muranyi, Zoltan
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p. 233 - 242
(2007/10/02)
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- Enzyme-catalyzed alcoholysis of flavone acetates in organic solvent
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Pseudomonas sp. lipase suspended in tetrahydrofuran was used to deacylate flavone acetates. Regioselectivity of the reaction has been observed.
- Natoli, Mariapina,Nicolosi, Giovanni,Piattelli, Mario
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p. 7371 - 7374
(2007/10/02)
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- SYNTHESE DE TRIHYDROXYPHENACYLIDENETRIPHENYLPHOSPHORANES UNE NOUVELLE VOIE D'ACCES AUX DIHYDROXYFLAVONES (CHRYSINE, ACACETINE...)
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An easy and convenient synthesys of two new trihydroxyphenacylidenetriphenylphosphoranes from phloroglucinol and pyrogallol is described.Some dihydroxyflavones are prepared by acylation of these ylids, intramolecular olefination and saponification of the two remaining ester groups.
- Le Floc'H, Yves,Lefeuvre, Martine
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p. 5503 - 5504
(2007/10/02)
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- Cleavage of Aryl Benzyl Ethers by Heterogeneous Catalytic Transfer Hydrogenation
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Aryl benzyl ethers are effectively debenzylated under heterogeneous catalytic transfer hydrogenation using Pd/C as catalyst and formic acid or its salts (sodium formate, ammonium formate and triethylammonium formate) as hydrogen donors.The method is illustrated with several examples from phenolic natural products.
- Krishnamurty, H. G.,Ghosh, Sanjukta,Sathyanarayana, S.
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p. 1253 - 1254
(2007/10/02)
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- Isolation of Pinocembrin from Goniothalamus grifithii and Its Biomimetic Synthesis
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The chloroform extract of the bark of Goniothalamus grifithii (Annonaceae) affords a known flavanone, pinocembrin (5,7-dihydroxyflavanone).A one-step biomimetic synthesis of (+/-)-pinocembrin involves heating phloroglucinol, cinnamic acid and polyphosphoric acid.
- Talapatra, Bani,Deb, Tulika,Talapatra, Sunil K.
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- A FLAVONE GLYCOSIDE FROM THE STEM OF IXORA ARBOREA
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A new flavone glycoside isolated from the stem of Ixora arborea has been characterized as chrysin 5-O-β-D-xylopyranoside on the basis of spectral data, colour reactions and degradation studies.Key Word Index - Ixora arborea; Rubiaceae; stem; chrysin 5-O-β-D-xylopyranoside
- Chauhan, J. S.,Kumar, Santosh,Chaturvedi, Rajesh
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p. 2404 - 2405
(2007/10/02)
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